Like Byron I tow with a Dodge Dakota. It has a V8 and 4X4. I don't require that much truck to tow the boler but I got it with the idea that if I upgrade I don't have to change tows unless I go Supersize and then I may have to get a full sized one. What changes your ratings is the addition of brakes to the trailer. Go back and read the threads on brakes, they will change your ratings. With NO brakes I would stay well below the weight of the tow. WITH brakes I would now go to the Mfg specifications.
Jim

My Excursion had a 10k lb tow rating with a 7,000 lb +/- curb weight. It handled a 9,000 lb trailer just fine, but IMHO the more weight you're towing, the more critical your towing equipment (hitch/brakes/controller) and their proper setup becomes.

My Excursion had a 10k lb tow rating with a 7,000 lb +/- curb weight. It handled a 9,000 lb trailer just fine, but IMHO the more weight you're towing, the more critical your towing equipment (hitch/brakes/controller) and their proper setup becomes.

Roger

I agree, Roger. The bigger the more caution.
But my problem with towing specs from the manufactures is that it is just a number on paper. I have no idea what rules they follow or how they arrive at a "safe" ratio. I trust myself more than them. So I'll probably never tow a big trailer without a bigger TV.

With NO brakes I would stay well below the weight of the tow. WITH brakes I would now go to the Mfg specifications.

I would not go up to the manf specs for tow limit, even with brakes, because most are caveated as being for relatively flat roads at sea level. Ford specifically recommends reducing the limit by 2% for every 1,000' of elevation. This is one reason why the rule of thumb among experienced trailer towers is not exceed 75-80% of the manf specs.

Suz, I went to the Dutch site you provided and tried an overweight combo. The results seem to be completely based on power of the tow vehicle rather than towing geometry (except weight ratio) and sway, but it's a good start.

At least there's something happening to standardize tow ratings. There's lots of standards written by SAE and I just guessed that there would be one on tow rating. There's standards on just about everything else.
Up to 3 years ago I had access to the printed version of all the SAE standards. Sometimes I miss the ability to look these things up, photo copy the standard, etc.

Just a comment about vehicle towing capability data. This data mainly relates to the tow vehicles structural capability and it's engine/transmission capability to pull a give size load. These ratings in no way speak to the dynamics, control, and stability of the tow vehicle/trailer combination. There are so many variables involved in in the stability and control of the combined vehicles that are out of the control of the tow vehicle designers that it would be impossible for them to design a vehicle that would fit every concievable trailer/tow vehicle combination.
Having said that, the ratio of tow vehicle weight to trailer weight can be a factor in resistance to loss of control due to trailer sway. Towing a 3500 # casita with a 7000 # Ford F350 will have more margin to resist a loss of control due to sway than say a 3500# Casita and a #3250 Subaru Forester. Admittedly, this is not all due to weight alone, wheelbase also is a factor.(Generally sppeaking though, heavier tow vehicles have longer wheelbases.) Cerrtainly tractor trailer rigs have different (lower) weight ratios but thethey are more affected by wind and other tractor trailers than by RV type trailers. (And they regularly have stability problems due to winds and their ability to remain controlable in avoidance manuvers is really limited.) They however can really play havoc with small RV trailers.
So don't discount the additional safety margin that larger tow vehicles provide when pulling small trailers. But since we all can't have TV weight /Trailer weights >>1, we need to know the limitation of our rigs, use sway conrol devices, and drive cautiously and keep are speed low enough to minimize stability problems.

That said, I don't think weight is that much of a factor if all the other stuf is right. [b] I have seen a small trailer yank a pickup truck around on the road when the loaded pickup weighed almost three times the loaded trailer's weight. Conversely, as PeterH points out, what's the weight ratio of a tractor-trailer rig hauling a load of structural steel...

I saw an empty, small utilitiy trailer yank a big Dodge Ram 2500 all over the hightway. That was a sight to remember ... one that my husband commented on for weeks.